Neutral deinking with a deinking composition comprising a lipase and a fatty acid ester

ABSTRACT

The present invention relates to methods for deinking wastepaper by pulping wastepaper at a pH between 4 and 8.5 in the presence of deinking agents comprising a lipase and a fatty acid ester and removing the thereby dislodged ink particles.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. application Ser. No.10/050,489, filed Jan. 16, 2002, which claims the benefit of U.S.provisional application No. 60/261,784, filed on Jan. 16, 2001, thecontents of which are hereby incorporated by reference.

TECHNICAL FIELD

[0002] The present invention relates, in general, to deinking ofwastepaper. In particular, the present invention relates to a deinkingprocess at neutral (pH 4-8.5) conditions.

BACKGROUND OF THE INVENTION

[0003] Wastepaper has long served as a source of raw fiber material forpapermaking. It has been standard practice in the art to reclaimwastepaper to allow the reclaimed paper fibers to be used as part or allof the stock of subsequent production of a variety of paper andpaperboard products. Today, greater utilization of reclaimed fibers hasprovided incentive for taking steps to upgrade the reclaimed products.These steps include treatment to effectively remove ink from wastefibers in order to permit their use in the manufacture of e.g. newsprintand high quality papers. Increasing amounts of e.g. old newspapers (ONP)and waste magazines (WM) are becoming available with increasedparticipation of end consumers in recycling.

[0004] In the course of conventional paper reclamation, deinkingprocedures include steps for converting the wastepaper to pulp andcontacting the pulp with an alkaline aqueous deinking medium containinga chemical deinking agent. The mechanical action and the alkalinity ofthe aqueous medium cause the partial removal of ink from the pulp fiber.The deinking agent completes this removal and produces an aqueoussuspension and/or dispersion of the ink particles. The resulting mixtureis subsequently treated to separate the suspended/dispersed ink from thepulp. This separation may be by flotation and/or washing techniquesknown in the art.

[0005] Conventional deinking chemicals comprise a complex mixture ofchemicals, e.g. sodium hydroxide, sodium silicate, chelating agents,hydrogen peroxide, surfactants, dispersants, collector chemicals andagglomeration chemicals. In general, it is standard in the prior artmethods to include a significant amount of alkaline material, since itis believed that the alkaline material is needed for sufficientsaponification and hydrolysis of the ink resins. In addition, mention ismade of the fiber swelling by the caustic being partially responsiblefor the detachment of ink particles from the fiber surface. Typically,the pH during such a deinking process is from about 9.5 to about 11.Exposing the cellulosic and lignocellulosic fibers to this degree ofalkalinity tends to cause yellowing of the fibers and, therefore, it isgenerally necessary to add an oxidative or reductive bleaching agent,such as peroxide. Furthermore, the alkaline method causes irreversiblechanges to the pulp fibers, and hence represents a cost to the facility

[0006] Thus, there is a need for a deinking process that operates underslightly acidic (from about pH 4) to slightly alkaline (to about pH 8.5)or neutral conditions, which is safe and which is economically andenvironmentally desirable.

[0007] It has been found by the present inventors that the use of adeinking agent, which comprises a lipase and a fatty acid ester,fulfills the above-mentioned requirements to such a deinking process.

SUMMARY OF THE INVENTION

[0008] Thus, the present invention relates to a method for deinkingwastepaper comprising the steps of

[0009] i) pulping the wastepaper at a pH between 4 and 8.5 in thepresence of deinking agent comprising a lipase and a fatty acid ester;and

[0010] ii) removing the thereby dislodged ink particles.

DETAILED DESCRIPTION OF THE INVENTION

[0011] The deinking agent suitable for the purposes described hereinshould include a lipase, which is active in the pH interval of fromabout 4 to about 8.5.

[0012] The lipase enzyme to be used in the present invention is one thatcan hydrolyze ester bonds. Such enzymes include, for example, lipases,such as triacylglycerol lipase (EC 3.1.1.3), lipoprotein lipase (EC3.1.1.34), monoglyceride lipase (EC 3.1.1.23), lysophospholipase,ferulic acid esterase and esterase (EC 3.1.1.1, EC 3.1.1.2). The numbersin parentheses are the systematic numbers assigned by the EnzymeCommission of the International Union of Biochemistry in accordance withthe type of the enzymatic reactivity of the enzyme.

[0013] The lipase may be a microbial lipase, e.g. from bacteria or fungisuch as Humicola or Pseudomonas, particularly lipase from H. lanuginosa(this lipase being referred to as Resinase A 2×®).

[0014] Preferred microbial lipases to be used in the methods of thepresent invention may be of bacterial, yeast or fungal origin, andsuitable examples include a lipase derived or obtainable from a strainof Humicola spp., Rhizomucor spp., Candida spp., Aspergillus spp.,Rhizopus spp. or Pseudomonas spp., especially from a strain of H.lanuginosa, Rh. miehei, C. antarctica, Aspergillus niger or Pseudomonascepacia. Specific examples of such lipases are lipase A and lipase B ofC. antarctica, described in WO 88/02775, the Rh. meihei lipase in EP 238023, the H. lanuginosa lipase described in EP 305 216, and the P.cepacia lipase described in EP 214 761 and WO 89/01032.

[0015] The lipase may be a native enzyme found in nature, or it may be avariant thereof obtained by altering the amino acid sequence. Examplesof such variants are those described in WO 92/05249, WO 94/25577, WO95/22615, WO 97/04079 and WO 97/07202, WO 98/08939, PCT/DK99/00068, EP99610010.3 and Danish patent application PA 1999 00441.

[0016] A specific example of a variant is the lipase from Humicolalanuginosa strain DSM 4109 having the mutations EISPPCGRRP, E99N, N101S,E239C, Q249R.

[0017] Specific examples of suitable, commercially available, lipasesare, e.g., Resinase A 2×, Novozyme 735, and Novozyme 525 (all availablefrom Novozymes A/S, Denmark).

[0018] The lipase used for the present invention may be obtained fromthe microorganism in question by use of any suitable technique. Forinstance, a lipase preparation may be obtained by fermentation of amicroorganism and subsequent isolation by a method known in the art, butmore preferably by use of recombinant DNA techniques as known in theart. Such method normally comprises cultivation of a host celltransformed with a recombinant DNA vector capable of expressing andcarrying a DNA sequence encoding the lipase in question, in a culturemedium under conditions permitting the expression of the enzyme andrecovering the enzyme from the culture. The DNA sequence encoding thelipase to be used may be of any origin, e.g. a cDNA sequence, a genomicsequence, a synthetic sequence or any combination thereof. Examples ofsuitable methods of preparing microbial lipases are described in, e.g.EP 0 238 023 and EP 0 305 216.

[0019] Lipase Units (LU) are determined according to the followingassay: Lipase activity (LU) is assayed using glycerine tributyrat as asubstrate and gum-arabic as an emulsifier. 1 LU (Lipase Unit) is theamount of enzyme which liberates 1 μmol titratable butyric acid perminute at 30° C., pH 7.0. The lipase activity can be assayed by pH-stattitration using e.g. a standard Radiometer titrator VIT90, obtainablefrom Radiometer, Copenhagen.

[0020] The lipase is typically added to the pulp in an amountcorresponding to 0.001% -0.15% % by weight of the dry pulp, preferablyin an amount corresponding to 0.010-0.10% by weight of the dry pulp,such as from 0.015-0.075% by weight of the dry pulp. These weightnumbers may, of course, vary considerably depending of the enzyme used,the specific activity of the enzyme, the applied pH, temperature, etc.It is, however, in general preferred that the lipase is added in anamount corresponding to at least 500 LU/kg dry wastepaper, preferably inthe range 500-500,000 LU/kg waste paper.

[0021] Further, the deinking agent suitable for the purposes describedherein should include a fatty acid ester.

[0022] In one embodiment of the invention, the fatty acid ester suitablefor the purposes described herein may be a methyl ester, an ethyl ester,a n-propyl ester, an isopropyl ester, a n-butyl ester, an isobutylester, a sec-butyl ester, a tert-butyl ester, a monoglyceride, adiglyceride or a triglyceride of a C₆-C₂₂ fatty acid, the C₆-C₂₂ fattyacid being optionally substituted with one or more hydroxy, ethoxy,n-propoxy and/or isopropoxy groups. In a preferred embodiment the fattyacid ester is a triglyceride.

[0023] In another embodiment of the invention, the fatty acid estersuitable for the purposes described herein is a C₆-C₂₂ fatty acid, whichhas been alkoxylated with ethylene oxide, propylene oxide, or acombination thereof. In a preferred embodiment the fatty acid ester is aC₆-C₂₂ fatty acid, which has been alkoxylated with ethylene oxide andpropylene oxide of the general formula

HO—(CH₂—CH₂—O)_(n)—(CH2-CH(CH₃)—O)_(m)—H,

[0024] Wherein n is an integer in the range from 3 to 25, and m is aninteger in the range from 2 to 14.

[0025] An example of commercially available fatty acid esters of theabove structure would include the Nopalcol® series(available from HenkelCorp.)

[0026] When used herein the term “C₆-C₂₂ fatty acid” is intended to meana (not substituted) saturated fatty acid or an (not substituted)unsaturated fatty acids comprising one or more double bonds, having atotal number of carbon atoms of from 6 to 22. Thus, the C₆-C₂₂ fattyacid may, in addition to the terminal carboxylic acid group, contain alinear or branched alkyl, hydroxyalkyl, alkenyl or hydroxyalkenylradical. As will be acknowledged by the skilled person, in case thefatty acid is substituted with, for example, ethoxy, n-propoxy and/orisopropoxy groups, the total number of carbon atoms in the fatty acidmoiety of the fatty acid ester may be larger, in some cases considerablylarger, than 22.

[0027] Specific examples of fatty acid moieties include caproic acid(6:0), enanthic acid (7:0), caprylic acid (8:0) pelargonic acid (9:0),capric acid (10:0) undecylenic acid (11:0), lauric acid (12:0),tridecylic acid (13:0), myristic acid (14:0), palmitic acid (16:0),stearic acid (18:0), palmitoleic acid (16:1), oleic acid (18:1), elaidicacid (18:1), ricinoleic acid (18:1), linoleic acid (18:2), linolenicacid (18:3) and mixture thereof, wherein the first number in thebrackets indicates the total number of carbon atoms in the fatty acidmoiety, whereas the second number indicates the number of double bonds.

[0028] In an embodiment of the invention the fatty acid ester (or moreprecisely, the C₆-C₂₂ fatty acid moiety of the fatty acid ester) issubstituted with one or more ethoxy and/or isopropoxy groups. In apreferred embodiment, the substitutent has the general formulae:

—(O—CH₂—CH₂)_(x)—(O—CH(CH₃)—CH₂)_(y)—OH,

—(O—CH₂—CH₂)_(x)—(O—CH₂—CH(CH₃))_(y)—OH,

—(O—CH(CH₃)—CH₂)_(y)—(O—CH₂—CH₂)_(x)—OH, or

—(O—CH₂—CH(CH₃))_(y)—(O—CH₂—CH₂)_(x)—OH,

[0029] wherein x is an integer in the range from 1 to 25, preferably inthe range from 1 to 10, and y is an integer in the range from 1 to 10,preferably in the range from 1 to 5.

[0030] As will be understood by the skilled person, the fatty acidesters suitable for the purposes described herein may be any of theabove fatty acid esters. Such esters may be used either individually orin admixture. For example, a number of commercially available fatty acidesters are available, which contains a number of the above-mentionedfatty acid esters. Specific examples of such commercially availableesters (or fatty acids which can easily be converted to esters bystandard method well known to the skilled person) include esters oftallow fatty acid, esters of butter fatty acids, esters of coconut fattyacids, esters of cottonseed fatty acids, esters of lard fatty acids,esters of olive fatty acids, esters of palm fatty acids, esters of palmkernel fatty acids, esters of peanut fatty acid, esters of peanut fattyacids, esters of soybean fatty acids, and esters of castor oil,including ethoxylated and propoxylated derivatives thereof. A specificexample of an ethoxylated and propoxylated derivative of castor oiltriglyceride is the Hartaflot G-5000 (available from Huntsman Corp.,Houston, Tex., U.S.A.). The approximate distribution of various fattyacids the above-mentioned commercially available products can be foundinter alia in Morrison and Boyd: Organic Chemistry. Fifth Edition. 1987,Allyn and Bacon, Inc., Boston, on page 1265.

[0031] The fatty acid ester is typically added to the pulp in an amountcorresponding to 0.025-1% by weight of the dry pulp, preferably in anamount corresponding to 0.05-0.75% % by weight of the dry pulp.

[0032] The fatty acid esters used for the purposes described herein arechemically unique compared to other surfactants commonly used indeinking wastepaper. Standard collector chemistry involves the use of afatty acid. Such fatty acids (typically used in the form of the calciumsalt) collect the ink upon liberation from the fibers, and keep themfrom being reattached to the fibers. Such fatty acid salts also allowthe liberated ink to be removed in the froth during the flotation stage,while the fibers remain behind.

[0033] The fatty acid esters described herein constitute a substrate forthe lipase, i.e. the fatty acid ester will, during pulping, be graduallyconverted into the corresponding fatty acid and the correspondingalcohol. This means that the added fatty acid/fatty acid ester systemfunctions as a “displector” class of surfactant. It serves both todisperse the ink from the fiber surface as well as to collect the ink toallow its removal during flotation. As it appears from the examplesherein, blank experiments have revealed that the lipase alone, i.e.without addition of fatty acid ester, did not dislodge ink particlesfrom the fiber surface.

[0034] Clearly, the double function of the fatty acid ester confers theadvantage that further dispersant and/or collectors may not benecessary.

[0035] The deinking agent would usually be supplied to the waste paperinitially, i.e. when the pulping stage commences. Alternatively, thedeinking agent may be supplied to wastepaper which is already in theform of a pulp, that is, to wastepaper which has first beensubstantially reduced to individual fibers. In the former case, thepulping step where the deinking agent is present is also sometimestermed “re-pulping”.

[0036] The lipase and the fatty acid ester of the deinking agent areprepared by conventional means. The lipase and the fatty acid ester maybe added to the waste paper either when pulping is initiated or may besupplied to the wastepaper which is already in the form of a pulp, thatis, to wastepaper which has first been substantially reduced toindividual fibers. The lipase and the fatty acid ester may be combinedprior to addition or the components can be added to the wastepaperindividually in any order.

[0037] Pulping can be conducted using any of the various conventionalprocesses and equipment designed for this purpose. Most conveniently,the wastepaper process feedstock is treated in a device known as a“hydrapulper”, which produces a slurry of the fibers in water.

[0038] Independently of whether the deinking agent is added to thewastepaper when the pulping stage commences or is added in a re-pulpingstage, it is preferred that the pulping with the deinking agent iscarried out for at the most 60 minutes, in particular for at the most 50minutes, e.g. for at the most 40 minutes, such as for at the most 30minutes, more preferably for at the most 20 minutes, such as for at themost 15 minutes, e.g. for about 10 minutes.

[0039] It is important to maintain an appropriate pulp slurrytemperature while the deinking agent is contacted with the pulp slurry.The temperature has to be consistent with the activity temperatureprofile of the lipase, and preferably the process is run at atemperature where the employed lipase has maximum activity. Since anumber of commercially available lipases have a substantial activity inthe temperature range of from 25 to 75° C. it is contemplated that theprocess can be run using temperatures, which do not deviatesubstantially from the temperatures normally used in such processes.Typically, pulping with the deinking agent is carried out at atemperature from 25 to 75° C., preferably from 30 to 70° C., such asfrom 35 to 65° C., e.g. from 40 to 60° C., more preferably from 45 to60° C., such as from 45 to 55° C., e.g. about 50° C.

[0040] The efficiency of the deinking agent can be significantlyinfluenced by the pH of the pulp slurry while contacting the deinkingagent with the pulp slurry, since fluctuations in the pH can result indeactivation of the lipase. As indicated above, the pH of the pulpslurry should be in the range of from 4 to 8.5. In a preferredembodiment of the invention, the pulping with the deinking agent iscarried out at a pH between 4.5 and 8.5, in particular between 5 and8.5, such as between 5.5 and 8.5, more preferably between 6 and 8.5,such as from 6.5 to 8.5, e.g., between 7.5 and 8.5. The pulp slurry pHhas to be consistent with the activity pH range of the lipase, and in apreferred embodiment the process is run at a pH where the employedlipase has optimal activity. The pH of the pulp may be adjusted by meansof buffering agents, such as sodium citrate, sodium carbonate, sodiumphosphate and the like. It is particularly preferred, however, thathydroxides, in particular alkali metal hydroxides, such as sodiumhydroxide, is not added at any stage, i.e. prior to, during or afterpulping.

[0041] The waste paper to be deinked according to the invention may beany reclaimed fiber, such as old newspapers (ONP), waste magazines (WM),mixed and sorted office waste, computer print outs, white ledger wastepaper, etc.

[0042] In a preferred embodiment of the invention the wastepapercomprises ONP, WM or a combination thereof.

[0043] In one embodiment of the invention the amount of ONP constitutesat least 10% by weight of the total amount of wastepaper, preferably atleast 20% by weight, e.g. at least 30% by weight, e.g. at least 40% byweight, more preferably at least 50% by weight, such as at least 60% byweight, e.g. at least 70% by weight, most preferably at least 80% byweight, such as at least 90% by weight, e.g. at least 95% by weight ofthe total amount of wastepaper. In a further embodiment of the inventionthe wastepaper consists essentially of ONP.

[0044] In another embodiment of the invention the amount of WMconstitutes at least 10% by weight of the total amount of wastepaper,preferably at least 20% by weight, e.g. at least 30% by weight, e.g. atleast 40% by weight, more preferably at least 50% by weight, such as atleast 60% by weight, e.g. at least 70% by weight, most preferably atleast 80% by weight, such as at least 90% by weight, e.g. at least 95%by weight of the total amount of wastepaper. In a further embodiment ofthe invention the wastepaper consists essentially of WM.

[0045] In a still further embodiment of the invention the wastepapercomprises 1-60% by weight of WM and 40-99% by weight of ONP, preferably10-50% by weight of WM and 50-90% by weight of ONP, such as 20-50% byweight of WM and 50-80% by weight of ONP, e.g. 30-50% by weight of WMand 50-70% by weight of ONP.

[0046] The consistency of the pulp will typically be in the range fromabout 0.5% to about 15%, preferably from 1 to 15%, such a from 2 to 15%,e.g. from 4 to 15%, more preferably from 6 to 15%, such as from 8 to15%, e.g. from 8 to 14%.

[0047] In addition to water, pulp and deinking agent, the pulp mayfurther contain substances conventionally employed in deinking process,e.g. brightening agents, solvents, antifoam agents and water softeners,in particular brightening agents.

[0048] Although not particularly preferred the pulp may also containadditional surfactants, such as non-ionic and cationic surfactants.Examples of non-ionic surfactants are, e.g., alkoxylated fatty acids,such as DI 600® from High Point Chemical Corp.; alkyl phenyl ethers ofpolyethylene glycol, such as the Tergitol®) series from Union Carbide;alkylphenolethylene oxide condensation products, such as the Igepal®series from Rhone Poulenc; and aryl alkyl polyether alcohols, such asRohm and Haas' Triton® X 400 series, e.g. Trition® X100. Examples ofcationic surfactants include imidazole compounds, such as Amasoft® 16-7and Sapamine® P from Ciba-Geigy and quaternary ammonium compounds, suchas Quaker® 2001 from Quaker Chemicals and Cyanatex® from AmericanCynamid.

[0049] The overall deinking process generally comprises pulping ormaceration of the wastepaper and ink removal by a flotation system, awater washing system or a combined flotation/washing system, A screeningor coarse cleaning stage can be utilized to remove contaminants such asglass, stone, metal and staples. A centrifugal cleaning stage (orstages) can be utilized to remove light weight materials such asplastic. Typical deinking processes are described in L. D. Fergusen“Deinking Chemistry: part 1” July 1992 TAPPI Journal pp. 75-83; L. D.Fergusen “Deinking Chemistry: part 2” August 1992 TAPPI Journal pp.49-58; and J. L. Spielbauer “Deinking System Overview” Voith Inc.Appleton, pp. 1-9.

[0050] It is known from WO 95/14807 that, in the case of starch coatedpaper, the deinking effect can be improved by including a treatment witha starch-degrading enzyme and, consequently, in a further embodiment ofthe invention, the pulping is carried out in the presence of a starchdegrading enzyme.

[0051] The starch-degrading enzyme is preferably an amylase, e.g. anα-amylase, a glucoamylase or a debranching enzyme. A single enzyme or acombination may be used, e.g. α-amylase together with glucoamylaseand/or a debranching enzyme. Examples of preferred α-amylases are thosederived from strains of Bacillus, e.g. B. amyloliquefaciens (B.subtilis), B. licheniformis or B. stearothermophilus and from strains ofAspergillus, e.g. A. oryzae. Examples of commercial products are BAN™,Termamyl®, Aquazyme Ultra™ and Fungamyl™ (products of Novozymes A/S).

[0052] Preferred glucoamylases are the glucoamylases derived from astrain of Aspergillus niger, e.g. the commercial product AMG (product ofNovozymes A/S).

[0053] The debranching enzyme is preferably a pullulanase, particularlyone derived from a strain of Bacillus acidopullulyticus, e.g. thecommercial product Promozyme® (product of Novozymes A/S).

[0054] In addition, it is well known that cellulases may aid thedeinking process. Furthermore, it is well known that cellulases mayimprove the drainability of the paper pulp. Consequently, in a stillfurther embodiment of the invention the pulping is carried out in thepresence of a cellulase.

[0055] Such cellulases are typically be derived from bacteria and fungi,such as Aspergillus niger, Trichoderma virde, Thielatia terrestris,Humicola sp. and Bacillus sp. The cellulase may be a mono component ormulti component cellulase, although mono component cellulases arepreferred. A class of cellulases that are especially useful arecellulases lacking a cellulose binding-domain (CBD). Cellulose-bindingdomains have been described by P. Tomme et al. in J. N. Saddler & M. H.Penner (eds.), “Enzymatic Degradation of Insoluble Carbohydrates” (ACSSymposium Series, No. 618), 1996. A number of cellulases are known tocontain a catalytic domain without a CBD; such a cellulase may be usedas such in the invention. It is also known that other cellulases containa catalytic domain and a CBD; such a cellulase may be truncated toobtain a catalytic core domain without the CBD, and this core may beused in the invention.

[0056] Cellulases may be classified into families on the basis ofamino-acid sequence similarities according to the classification systemdescribed in Henrissat, B. et al.: Biochem. J., (1991), 280, p. 309-16,and Henrissat, B. et al.: Biochem. J., (1993), 293, p. 781-788. Somepreferred cellulases are those belonging to Family 5, 7, 12 and 45.

[0057] A preferred Family 5 cellulase without CBD is an alkalinecellulase derived from a strain of Bacillus. One such Family 5 cellulaseis the endo-glucanase from Bacillus strain KSM-64 (FERM BP-2886). Thecellulase and its amino acid sequence are described in JP-A 4-190793(Kao) and Sumitomo et al., Biosci. Biotech. Biochem., 56 (6), 872-877(1992). Another Family 5 cellulase from Bacillus is the endo-glucanasefrom strain KSM-635 (FERM BP-1485). The cellulase and its amino acidsequence are described in JP-A 1-281090 (Kao), U.S. Pat. No. 4,945,053and Y. Ozaki et al., Journal of General Microbiology, 1990, vol.136,page 1973-1979. A third Family 5 cellulase from Bacillus is theendo-glucanase from strain 1139. The cellulase and its amino acidsequence are described in Fukumori F. et al., J. Gen. Microbiol.,132:2329-2335 (1986) and JP-A 62-232386 (Riken). Yet another preferredFamily 5 cellulase without CBD is an endo-beta-1,4-glucanase derivedfrom a strain of Aspergillus, preferably A. aculeatus, most preferablythe strain CBS 101.43, described in WO 93/20193 (Novo Nordisk).

[0058] The Family 7 cellulase may be derived from a strain of Humicola,preferably H. insolens. An example is endo-glucanase EG I derived fromH. insolens strain DSM 1800, described in WO 91/17244 (Novo Nordisk).The mature cellulase has a sequence of the 415 amino acids shown atpositions 21-435 in FIG. 14 of said document and has a specific activityof 200 ECU/mg (based on pure enzyme protein). This cellulase may furtherbe truncated at the C-terminal by up to 18 amino acids to contain atleast 397 amino acids. As examples, the cellulase may be truncated to402, 406, 408 or 412 amino acids. Another example is a variant thereofdenoted endo-glucanase EG I* described in WO 95/24471 (Novo Nordisk) andhaving a sequence of 402 amino acids shown in FIG. 3 therein.

[0059] Alternatively, the Family 7 cellulase may be derived from astrain of Myceliophthora, preferably M. thermophila, most preferably thestrain CBS 117.65. An example is an endo-glucanase described in WO95/24471 (Novo Nordisk) comprising the amino acids 21-420 and optionallyalso the amino acids 1-20 and/or 421-456 of the sequence shown in FIG. 6therein. As another alternative, the Family 7 cellulase may be derivedfrom a strain of Fusarium, preferably F. oxysporum. An example is anendoglucanase derived from F. oxysporum described in WO 91/17244 (NovoNordisk) and Sheppard, P. O. et al., Gene. 150:163-167,1994. The correctamino acid sequence is given in the latter reference. This cellulase hasa specific activity of 350 ECU/mg.

[0060] A preferred Family 12 cellulase without CBD is CMC 1 derived fromHumicola insolens DSM 1800, described in WO 93/11249 (Novo Nordisk).Another preferred Family 12 cellulase without CBD is EG III cellulasefrom Trichoderma, particularly Trichoderma viride or Trichoderma reesei,described in WO 92/06184 (Genencor). Alternatively, the Family 12cellulase may be derived from a strain of Myceliophthora, preferably M.thermophila, most preferably the strain CBS 117.65. Such a cellulase(termed C173) can be produced by cloning DNA from CBS 117.65, andsubsequently transforming Aspergillus oryzae, a non-cellulolytic hostorganism, and expressing the cellulase by cultivation of the transformedhost, and separating the only cellulolytic active ingredient from theculture broth. C173 has optimum activity at pH 4-6.5, a specificactivity of 226 ECU per mg protein and a molecular weight of 26 kDa (forthe mature protein). The sequence of cDNA encoding C173 (from startcodon to stop codon) and the amino acid sequence of the mature proteinof C173 are shown in the sequence listing as SEQ ID NO: 1 and 2.

[0061] A preferred Family 45 cellulase without CBD is the EG V-corederived from Humicola insolens, described in Boisset, C., Borsali, R.,Schulein, M., and Henrissat, B., FEBS Letters. 376:49-52,1995. It hasthe amino acid sequence shown in positions 1-213 of SEQ ID NO: 1 of WO91/17243 (Novo Nordisk). Another preferred Family 45 cellulase withoutCBD is FI-CMCase from Aspergillus aculeatus described by Ooi et al.,Nucleic Acids Research, Vol. 18, No. 19, p. 5884 (1990).

[0062] Examples of commercially available cellulases include Novozym613, Novozym 476, and Novozym 342 (all available from Novozymes A/S,Denmark)

[0063] The invention is further illustrated by the followingnon-limiting examples.

Materials and Methods Equipment

[0064] Methrohm transportable pH meter 704; Hobart N-50 mixer equippedwith a jacketed bowl attached to a constant temperature bath; Lamort 17l laboratory flotation deinking device; Tappi handsteet mold and Tappihandshteet press; Macbeth Color-Eye 7000 spectrophotometer

Enzymes

[0065] Novozyme 735, Batch LDN00010., activity 5 KLU/g

[0066] Lecitase 10L, Batch L846-002, activity 10 KLU/g

[0067] Novozyme 525 L, Batch PPW 6354. activity 15 KLU/g

[0068] Resinase A 2×, activity 100 KLU/g

Chemicals and Raw Materials

[0069] The ONP for these experiments was prepared by tearingapproximately 1″ squares from a batch of Wall Street Journals that wereless than two months old.

[0070] Hartaflot G-5000, an ethyloxylated and propoxylated castor oilderivative, was obtained from Huntsman Chemicals

EXAMPLES Example 1 Enzymatic Deinking

[0071] Hot tap water (750 ml) was placed in a jacketed Hobart mixer bowlwith an external water bath set to provide a temperature of 50° C. forthe contents of the bowl. The Hartflot G-5000 (0.22 g) was added to thebowl. The wastepaper (165 g) was then added and allowed to wet outbefore agitation was initiated. After agitation was initiated anadditional 750 ml of hot tap water was added stepwise in order to avoidsplashing. Agitation was stopped and the pH of the pulp slurry wasadjusted to approximately 6.5 by addition of 10% sodium carbonate.

[0072] Low speed agitation was then started and the lipase was added.Agitation was continued for 20 minutes after which the pulp was diluted5 liter. The pulp was then added to the Lamort deinking cell (capacity:17 liter). The cell was filled almost to the top, agitation wasinitiated and less than 1 liter of pulp was removed to serve as the“pre-float” sample. The cell was then again filled to the top with hottap water, the agitator was set to 1050-1100 rpm and the deinkingprocess begun; During a 10 min. period the foam was scraped from thecell and collected to allow determination of the amount of rejects.

[0073] After the 10 min. flotation period the pulp was collected 1.2 g(approximately) hand-sheets were prepared from the pulp. The handsheetswere prepared according to Tappi Test Method T-205. An additional set ofhandsheets was made, wherein the initially formed handsheets werebackwashed by refilling the sheetmold with water and the handsheets wereformed again. These handsheets are identified by the term “backed”.

[0074] Brightness measurements of the air-dried handsheets were doneusing the Macbeth Coloreye unit equipped with the software to convertthe optical data to Tappi Brightness values. The brightness readingswere made on the smooth (wire) side of the handtsheets. The individualhandsheet being measured was backed up by using the stack otherhandsheets of the series while the readings were being made.

[0075] The observed results are compiled in the below Table 1. TABLE 1Observed pH % Tappi Brightness Run Lipase/Surfactant Initial End %Rejects Pre-float Post-float Back-wash 1 None/None 6.5 6.2 4.5 43.3 46.149.0 2 87 mg Novozym 735/ 6.4 6.1 4.5 44.6 46.4 48.4 None 3 94.7 mgNovozym 6.3 5.8 6.3 44.0 48.0 50.2 735/0.23 g Hartaflot G-5000 4 55 mgLecitase*/0.22 g 6.5 6.2 5.4 44.8 47.9 50.5 Hartaflot G-5000 5 35 mgNovozym 525/0.22 g 6.6 6.3 7.8 43.6 47.1 49.0 Hartaflot G-5000

[0076] As it appears the lipases, when used alone, were practicallyunable to dislodge ink from the wastepaper. Furthermore, it can be seenthat the lipase/fatty acid ester deinking agent is capable of dislodgingsignificantly more ink (higher brightness values) as compared to theblank (no lipase and no surfactant) or the experiment, wherein only thelipase was added.

Example 2 Surfactant Hydrolysis

[0077] Hartaflot G-5000 (0.42 g) was dissolved in 1500 ml water placedin a jacketed Hobart mixer bowl. The external water bath was set toprovide internal temperatures close to those used for the earlierdeinking trials. The initial pH was adjusted with 10% sodium carbonateto the value mentioned as the zero-time value in the table. Onceadjusted, it was followed by the addition of lipase. 96 mg Novozym 735was used and 24 mg Resinase A 2× were used, which correspond to theamounts used in the deinking trials. The pH change was monitored using ahandheld pH meter and data was collected after 0, 10, 20, 40 and 60 min.

[0078] The observed results are compiled in the below Table 2. Time(min) 0 10 20 40 60 Rate of hydrolysis by change of pH: Novozym 735 7.256.72 6.67 6.35 6.22 Resinase A 2x 7.79 7.68 7.52 7.35 7.25

1. A method for deinking wastepaper comprising the steps of i) pulpingthe wastepaper at a pH between 4 and 8.5 in the presence of deinkingagent comprising a lipase and a fatty acid ester; and ii) removing thethereby dislodged ink particles.
 2. A method according to claim 1,wherein the consistency in step i) is from about 0.5% to about 15%.
 3. Amethod according to any of the preceding claims, wherein the wastepapercomprises old newspapers (ONP).
 4. A method according to claim 3,wherein the amount of ONP constitutes at least 10% by weight of thetotal amount of wastepaper.
 5. A method according to claim 4, whereinthe wastepaper consists essentially of ONP.
 6. A method according to anyof claims 1-2, wherein the wastepaper comprises waste magazines (WM). 7.A method according to claim 6, wherein the amount of WM constitutes atleast 10% by weight of the total amount of wastepaper.
 8. A methodaccording to claim 7, wherein the wastepaper consists essentially of WM.9. A method according to any of claims 1-2, wherein the wastepapercomprises ONP and WM.
 10. A method according to claim 9, wherein thewastepaper comprises 1-60% by weight of WM and 40-99% by weight of ONP.11. A method according to any of the preceding claims, wherein thepulping with the deinking agent is carried out at a pH between 4.5 and8.5.
 12. A method according to any of the preceding claims, wherein thepulping with the deinking agent is carried out at a temperature from 25to 75° C.
 13. A method according to any of the preceding claims, whereinthe fatty acid ester is a methyl ester, an ethyl ester, a n-propylester, an isopropyl ester, a n-butyl ester, an isobutyl ester, asec-butyl ester, a tert-butyl ester, a monoglyceride, a diglyceride or atriglyceride of a C₆-C₂₂ fatty acid, the C₆-C₂₂ fatty acid beingoptionally substituted with one or more hydroxy, ethoxy, n-propoxyand/or isopropoxy groups.
 14. A method according to any of claims 1-13,wherein the fatty acid ester is a C₆-C₂₂ fatty acid, which has beenalkoxylated with ethylene oxide, propylene oxide, or a combinationthereof.
 15. A method according to claims 13 or 14, wherein the fattyacid moiety of the fatty acid ester is selected from the groupconsisting of caproic acid (6:0), enanthic cid (7:0), caprylic acid(8:0) pelargonic acid (9:0), capric acid (10:0) undecylenic acid (11:0),lauric acid (12:0), tridecylic acid (13:0), myristic acid (14:0),palmitic acid (16:0), stearic acid (18:0), palmitoleic acid (16:1),oleic acid (18:1), elaidic acid (18:1), ricinoleic acid (18:1), linoleicacid (18:2), linolenic acid (18:3) and mixture thereof.
 16. A methodaccording to claims 13 or 14, wherein the fatty acid moiety of the fattyacid ester is substituted with one or more ethoxy and/or isopropoxygroups.
 17. A method according to claim 16, wherein fatty acid moiety ofthe fatty acid ester is substituted with ethoxy and isopropoxy groups ofthe general formulae —(O—CH₂—CH₂)_(x)—(O—CH(CH₃)—CH₂)_(y)—OH,—(O—CH₂—CH₂)_(x)—(O—CH₂—CH(CH₃))_(y)—OH,—(O—CH(CH₃)—CH₂)_(y)—(O—CH₂—CH₂)_(x)—OH, or—(O—CH₂—CH(CH₃))_(y)—(O—CH₂—CH₂)_(x)—OH, wherein x is an integer in therange from 1 to 25, and y is an integer in the range from 1 to
 10. 18. Amethod according to claim 17, wherein x is an integer in the range from1 to 10, and y is an integer in the range from 1 to
 5. 19. A methodaccording to any of claims 14-18, wherein the fatty acid ester is atriglyceride.
 20. A method according to claim 19, wherein the fatty acidester is Hartaflot G-5000™.
 21. A method according to any of thepreceding claims, wherein the pulping step is carried out in thepresence of a starch degrading enzyme.
 22. A method according to claim21, wherein the starch degrading enzyme is an amylase.
 23. A methodaccording to any of the preceding claims, wherein the pulping step iscarried out in the presence of a cellulase.
 24. A method according toclaim 23, wherein the cellulase is a mono component cellulase.
 25. Amethod according to claim 24, wherein the cellulase lacks a cellulosebinding domain.
 26. A method according to any of the preceding claims,wherein the lipase is added in an amount corresponding to 0.001-0.15% byweight of the dry pulp.
 27. A method according to any of the precedingclaims, wherein the fatty acid ester is added in an amount correspondingto 0.025-1% by weight of the dry pulp.